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Who owns this abandoned airplane?
I am trying to buy an abandoned aircraft on my airfield in France. The problem is, since 2012, the aircraft is abandoned in French government Hangars.
The Beechcraft Duke is de-registered since 2012 and has never been registered since now on. The owner vanished, nobody knows if he is still alive. I have been in contact with the FAA, apparently he never answered of the letters the have send him.
My questions are: who is the owner of this aircraft at this precise moment? Is it an abandoned aircraft? No owner? No registration? What is the administrative status?
Here is more information about the aircraft:

Manufacturer: Beech
Model:    B-60 Duke    Search all Beech B-60
Year built:   1975
Construction Number (C/N):    P-367
Aircraft Type:    Fixed wing multi engine
Number of Seats:  6
Number of Engines:    2
Engine Type:  Reciprocating
Engine Manufacturer and Model:    Lycoming TIO-541-E1C4
Also Registered As:   G-DUKE
De-registered  Cancel: 1982-02-10
Aircraft Registration Number: N6779S
Mode S (ICAO24) Code: A8F95D
Certification Class:  Standard
Certification Issued: 1985-08-23
Air Worthiness Test:  1982-03-03
Last Action Taken:    1993-04-24
Current Status:   Undel Tri Owner
Registration Type:    Individual
Address:  Portland, OR 97210 United States
Region:   Northwest Mountain

The question of who is the owner is a legal matter, not an aviation one.  Whether you can get it certified for flight is another matter, but perhaps best to sort out the first issue first.

According to flightaware this aircraft flew in New York State in 2018. There must be a mixup somewhere?

maybe the registration N6779S has been given to another aircraft. since it has been deregistered in 2012, the registration doesn't belong to the duke anymore?

so I need to get in touch With M.Posnansky...?

It doesn't appear that N6779S has been reassigned. But it could be a mixup somewhere else in the system.

The owner appears to be the same as the (shared) owner, designer and builder of N15PF, which has a Wikipedia page. This registration is active and also lists another owner who you might be able to contact.

The mailing address for Fronius is literally on the FAA registration. But you should probably just hire a private investigator who can make contact.

The last registered owner of the aircraft is Mr. Hernan Posnansky. Since he seems to be alive and well, you should make him an offer for it.

Hello M.Jimenez, thank you for your answer. I think I'll have to find one his daughter and asked her to give me the aircraft. I am sure she doesn't even know that her father had a duke abandonned in LFGB. let's try to find Mme.Posnansky ... if her name is still the same.

He may also be alive but in a care home or otherwise unable to react to any of this. Many possibilities.

It's been 1 week now I am trying to find his daughter. I found on facebook his first wife and her son, I wrote them a message but no answers. So I tried to find his second wife who used to live in Zurich, close to where I live. Without success for the moment. I think it would be easier to work with a detective at this point.

No, it would be easier to hire an attorney with experience in French aviation law and abandoned aircraft. The attorney can advise you as to the law and then take whatever actions are required. A detective may not find anyone and that's all they can do.

My husband’s last communication with Hernan Posnansky was sometimes in September 2021 and at that time he was in Zurich and seeking contact with a faculty member of the Technical University. No contact since that time. Hernan’s age will be roughly 78.
To the best of our knowledge he was only married once.
Sharon de Piolenc

Fyi, Mr Posnansky is alive and well and has just rejoined our EAA Chapter, www.EAA240.org today, July 8 2023.

Hello!  Would you have the chance to ask him if he’s ok to have chat with me ? E-mail? Phone number? Anything !


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Does Russia still use a Snowtam to report normative brake friction?
Does Russia still use the normative (Russian) brake friction when reporting Snowtams for their airports? What about former Soviet (CIS) countries?

Long story short, as best I can tell everywhere except Kazakhstan uses the ICAO SNOWTAM format. Kazakhstan uses two different Russian formats depending on what airport you're at, which is an interesting approach to say the least.
First, the Russian format is described here, it's a decimal value where less than 0.31 is "unreliable" and more than 0.41 is "good". In fact, there are two Russian values: the "raw" value as measured directly by a friction device, and the "normative" value that is derived from the raw one (although I couldn't find any explanation of how). I guess that the raw value is supposed to be the actual coefficient of friction.
The ICAO format, on the other hand, is an integer value from 1 to 5.
(Incidentally, I'm aware that I'm blurring the distinction between format and values here, but since there is so little definite information on this topic available - at least in English - I don't think it matters much.)
The Russia and CIS AIP includes a Snow Plan 2013-2014 that states:

[...] friction coefficient will be distributed by means of SNOWTAM in
  ICAO format (Annex 15)

That immediately suggests that Russia and the CIS now use the ICAO format, and considering the lack of any information about Russian format SNOWTAMs in the AIP or on the web in general, it seems very likely that the ICAO format is now the main or only one in use.
However, Kazakhstan appears to be an exception. There is a permanent NOTAM for Almaty airport (ICAO: UAAA) in Kazakhstan that includes this remark:

K0706/13 NOTAMN Q) UAAA/QFBCS/IV/M/A/   /   /4321N07702E A) UAAA B)
  1312010001 C) PERM E) AT ALMATY AERODROME THE INFORMATION ON RUNWAY
  BRAKING ACTION IS TRANSMITTED BY ATIS AS FOLLOWS: IN ENGLISH-IN VALUES
  OF ESTIMATED SURFACE FRICTION RELATIVE TO MEASURED ''SFT'' FRICTION
  COEFFICIENTS. IN RUSSIAN-IN NUMERICAL VALUES OF NORMATIVE ''RUSSIAN''
  FRICTION COEFFICIENTS.

There is a very similar NOTAM for Shymkent (ICAO: UAXX) that includes this almost-but-not-quite-the-same remark:

K0707/13 NOTAMN Q) UAXX/QFBCS/IV/M/A/   / A) UACC UATT UAII B)
  1312010001 C) PERM E) AT ALL AERODROMES EXCEPT ALMATY THE INFORMATION
  ON RUNWAY BRAKING ACTION IS TRANSMITTED BY ATIS OR ATC AS FOLLOWS: IN
  ENGLISH-IN VALUES OF ESTIMATED SURFACE FRICTION RELATIVE TO NORMATIVE
  ''RUSSIAN'' FRICTION COEFFICIENTS. IN RUSSIAN-IN NUMERICAL VALUES OF
  NORMATIVE ''RUSSIAN'' FRICTION COEFFICIENTS.

There is no similar NOTAM for any major Russian airport.
If I put all this information together, it appears that:

Russia and the CIS now use the ICAO format for SNOWTAMs
Almaty in Kazakhstan reports braking action in the 'raw' Russian format
All other Kazakhstan airports report braking action in the 'normative' Russian format

Very interesting. As of today (December 2019), the Russian format seems to be in effect at least in Karaganda, Kazakhstan, with the added surprise that „point three“ (0.3), as reported by Tower, was sold as equivalent to braking action „good“, which it wasn‘t.

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Would it be feasible to develop a dirigible-based refueling station for fighter aircraft?
The impossibly bad 2005 film Stealth featured a dirigible-based, mid-air refueling tanker station for the stealth fighters to use.
At first, this seemed like it might have been the singular good idea in the film as a dirigible would have a very long loiter time making it ideal for fighter refueling.
But I don't think it's possible, right? What is the maximum known air speed of a dirigible vs. the lowest possible air speed for a tactical fighter?
(Note: I do think it'd be possible for helicopters and osprey to use a dirigible tanker, right, as their stall speeds can be essentially zero?)

A stationary (or very slow), big, fat target full of fuel.  What could possibly go wrong?

If you're ferrying aircraft, you can put the big fat tanker right in the middle of atlantic where presumably there aren't that many bad guys.

So now we are ferrying helicopters and Ospreys across the Atlantic?  I don't think you've thought this through ;)

My question is mainly about fighters. How else do you get the across oceans quickly? In air refueling is often your best choice.

Also, current refuelling tankers (airplanes) are also slow, big, and fat and not very maneuverable... just saying.

One possible solution is to have a big tire shaped thing, and the fueling nozzle and the receiving aircraft flies around it at high speed while the tanker just floats still.

Love the "tire shape thing". I refer to it as "the doughnut shaped Hindenberg", and had considered it as a portable satellite launch pad.

Your third paragraph is spot on.  It is the kind of insight that should have caused you to realize that the idea is so far fetched that it is probably not worth asking about.  Listen to your common sense... trust it!  ;)

What is the maximum known air speed of a dirigible vs. the lowest possible air speed for a [stealth] fighter?

Airship fastest speeds
According to Guinness the world record speed for an airship was 70 mph by Steve Fosset in 2004.
Guinness also say

The large rigid airships built by the USA and Germany in the 1920s and 30s could reach higher speeds (up to 140 km/h or 87 mph according to some sources), but these were never officially measured to FAI standards.

Stealth aircraft slowest speeds
The F-117 has a landing speed of 180 mph.
The F-35B is stealthy and can hover.

At 140kph it's actually quite promising. With thrust vectoring and current state-of-the-art FBW, it's not impossible to hover at 140kph (even without thrust vectoring, 160kph hovering has been demonstrated in various air shows).

@user3528438 isn't the definition of hovering that you have little or no forward speed? What do you mean that 160kph hovering has been demonstrated? And I think in this case, since dirigibles can remain airborne at zero airspeed (citation needed), then if the fighter can hover (my definition of hover) then, at least as far as speed goes, the two aircraft are compatible.

It is likely that at a hover you are burning fuel as fast as you are taking it on.  Even if not, the idea is impractical when we already have proven solutions.

Another factor to be considered... getting the tanker to where it is needed.
Aerial refueling is exclusively a military thing - far too expensive for commercial use. Tankers are needed where the conflict is.
One can imagine a regional conflict brewing up in a remote location, and the air forces unable to provide support until the dirigible plodded along to the location at 70 or so mph... a few days later.
Tankers that can keep up with the fighters and ground attack aircraft not only are fast enough to refuel with the fighters at a relatively safe speed, they can also get to where they are needed at the same time the attack aircraft can.
Also, being slow and very large, a dirigible would make a very easy target.

It is not possible, and it is not a good idea.
It is not possible, because fighter aircraft are very hard to control at low speeds. Even though some aircraft are hover-capable, air-to-air refueling takes a long time and requires incredible precision. Holding the position required to connect to the boom or drogue is hard enough at 270 knots, where the aircraft is easier to control—doing it at low speeds or during a hover would be nearly impossible. Further, maintaining connections for the 5-10 minutes required to transfer fuel would be even worse. Finally, this would force the aircraft down to a hover-able height (for F-35s this is apparently at 10,000 feet or lower), which would cost the plane valuable fuel, time and energy when it had to climb back up to 25-30,000 feet.
It is not a good idea, because tankers already excel at the job and can cover more requirements than just refueling. First of all, tankers can carry an enormous amount of fuel. A KC-10 Extender can carry 365,000 lbs of fuel, that's (exactly) 20 full tanks for an F-35A. Second, they have decent cruise speeds, long range and high station time. Finally, they can carry other cargo than just fuel. These facts combined means that when a squadron deploys to a theater, they can be accompanied by a tanker for the entire flight. This will not only allow the tanker to extend (heh) the practical range of the fighters it accompanies, but it can also carry personnel and equipment required for the squadron that will not fit in the fighters. This is exactly how squadrons were deployed to the Middle East for Desert Shield, for example.
Finally, the dirigible-based tanker would be an even easier target than a tanker aircraft, and would likely be detected and destroyed by hostile forces more or less immediately after hostilities broke out. Due to its low speed, it would be easy for a missile's radar to pick it out and target it specifically, and evasion would be impossible.

Feasible: yes
Practical: no
Fighters without hover capability could not directly refuel from it due to the airspeed, but it could serve as a "carrier depot", semi-permanently camped out mid-Atlantic high above the clouds -- Large tankers could supply it, while small tankers would dock with it (empty), load up with fuel ready to take to an operations theater faster than a land-based tanker could manage.  Alternatively land based tankers could refuel and top up to larger than take-off capacities to carry to an operations theater.
However, it would be too easy a target to be useful in any world-powers operation, so at best would serve only as a stop-gap rapid-deployment readiness capability with too large an operations cost to justify.

You mean a dirigible as in lighter-than-air aircraft?
So it has a long loiter time - it has to get the load up there
A lighter-than-air aircraft is not designed for a payload
Nitrogen is about 5.4 liters per pound
Hydrogen is about 0.4 liters per pound
A 10,000 lb payload is a balloon about 40 meters across
The problem is once you get it up there and dump 10,000 lbs of fuel you have to get is back to the ground.
Release a bunch of hydrogen to get it back to the ground is not exactly an ideal situation.  Hydrogen is combustible and not cheap.
10,000 lbs is about one fighter.
100,000 lbs is about 10 planes and now 80 meters in diameter.
100 planes (1,000,000 lbs) for like a mid Atlantic fuel station would be 170 meters in diameter. It just does not seem realistic to me. If it is big enough to get the load up there it is less than stealth.
The cost of the hydrogen to float jet fuel cost more than the jet fuel itself.  Hydrogen is fuel and is going to have at a minimum fuel cost.  So robokaren it is produced by (simple) electrolysis of water.  The water is cheap.  The energy to separate the hydrogen is the cost of energy and energy is not cheap.

This is factually incorrect. dirigibles have plenty of payload.

@Federico Then please explain how a "lighter-than-air" aircraft has plenty of payload?  Air is pretty lite.

I would suggest you read something about Zeppelins, they were used for transatlantic flights. Also others were used for the exploration of the north pole (Norge, Italia) and they carried plenty of personnel and equipment.

@Federico Personnel and equipment is way different than a cargo craft.    Explore the pole is distance not cargo.  Show me the facts (physics) on how on a lighter than air is going to carry 10,000 lbs of fuel.

The Hindenburg had a payload twice as much: https://en.wikipedia.org/wiki/Hindenburg-class_airship#Specifications Useful lift: 10,000 kg (22,046 lb)

@Federico OK, so now you drop the load (fuel).   How do you get it down?

If you're using hydrogen, you "burn" it using fuel cells getting both electricity and water, which you use for ballast.  Your other factual inaccuracy is that hydrogen's really cheap -- you can electrolyze it from water again. It's helium that's expensive and rare.

@RoboKaren Did you vote me down?  Define cheap.  Electrolysis is not cheap.

The LEMV hybrid airship (HAV-304 / Airlander 10) obtains 40% of its lift from aerodynamic forces and its engines can provide  25% lift. So a vehicle of this sort has options other than jettisoning hydrogen in order to balance lift when payload weight is removed. Other airships use ballonets to adjust lift.

@RedGrittyBrick So other options.  From a payload perspective alone do you think it is feasible as a mid Atlantic fueling station.  Even the high capacity HAV is about 10 jets of fuel and it is not designed to come back down after dropping off the load.  To me 10 is not a fuel station.  Take a load up and drop it off you are fighting buoyancy in both directions.

Oh, I know, the downvoters are part of a consortium selling "new wave" dirigibles for 1 billion taxpayer $ each

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Why is this plane flying in circles?
I've been watching this flight after they declared a general emergency and now they are following this oval flight path. Why would that be?

`cos flying in squares is difficult, and triangles is impossible.

@Criggie Well, ... https://www.npr.org/sections/thetwo-way/2017/08/04/541595580/boeing-dreamliner-crew-draws-enormous-outline-of-their-plane-in-the-sky

@ralphJ  Well now, that's just showing off !

That track is a holding pattern. Aircraft fly in a holding pattern most commonly in busy airspace, to create a gap between them and other aircraft in front.
This particular flight is probably flying in the holding pattern while they troubleshoot the technical problem, or to burn off excess fuel to get to a lower weight, or simply to give the pilots time to get ready for landing. A holding pattern is much better than just flying in a straight line and going far away from the airport.

An aircraft cannot just stop in flight, like a car stopping on the roadside. So when it needs some delay the crew  flies this pattern, called a holding pattern, consisting in flying a leg of about 2 minutes, flying back and repeating as long as required.
In this case it was a Boeing 737-800 from Egypt Air, registered SU-GCM. As you saw it was squawking 7700 (emergency) after an engine failure.
From Aviation Herald:

the crew stopped the climb, initiated a descent and entered a hold.

They needed time perhaps to perform the emergency checklists, assess the situation and decide with the operator management the best option for the flight.
We don't know yet the cause nor whether the crew was able to restart the engine. After an engine shutdown and a successful restart, there is this checklist item:

Run the engine for three minutes at idle thrust

They decided to return to their airport of origin.

Source: FR24.
It took off again a few hours later.

Holding pattern
From SKYbrary:

Holding patterns are flown as a delaying tactic,

be it for ATC requirements such as airspace saturation or approach delays,
as the published termination of a missed approach procedure to be flown whilst coordinating further clearance,
at pilot request to allow time for completion of abnormal or emergency checklist procedures or at any other time that a delay in flight progress is required.
Under Instrument Flight Rules (IFR) pilots are expected to adhere to proscribed holding procedures inclusive of speed, hold entry procedures, timing and rate of turn, as the protected airspace for the holding pattern, and thus separation from other traffic, is predicated on those procedures.

Holdings ("stacks") are often seen near busy airports, e.g. see this animation from NATS, the ATC service in UK:

Engine failure
Losing an engine is not catastrophic, there is another one able to power the aircraft safely. But as a second failure would be a real emergency (not necessarily fatal), the crew must stop the flight and land, preferably at an airport where the engine can be checked and repaired.
A failed engine shouldn't be a cause of worry for passengers. The probability the second  engine fails is tiny. E.g. twin-engine aircraft are allowed to fly without any airport available in a radius of 3 hours if the operator can demonstrate an average in-flight failure rate smaller than 0.02 per 1000 hours. With such rate the probability to have a dual failure within a period of 4 hours is $\small 6.4 \times 10^{-9}$ (thanks to @mbrig for fixing my calculation) compared to $\small 7.2 \times 10^{-9}$ for winning a typical lottery.

@mins I not sure it matters much in terms of "valid degree of worrying" for the passengers whether the causes are independent or correlated. Though I think most of them will manifest pretty quickly, so I guess we can say that if the second engine holds out for 10+ minutes (?) you are probably not a victim of something that will affect both.

If we're going to get into the statistics philosophy though... once one engine has failed, we can't say the probability of a dual failure is (single failure)^2 any more. The chance the second engine fails is the same as it was before, 0.02 per 1k hours...

@mbrig Note that once an engine has failed there is no squaring any longer! Additionally, there are reasons to assume that there is an underlying reason that may affect the second engine equally (e.g. fuel issues, unreliable model, shoddy maintenance, end-of life or end-of service interval). Therefore, the probability for the second engine to fail as well may be much higher than the across-the board mean probability for any engine.

@Peter-ReinstateMonica: Of course engines cannot be said completely independent, and causes of dual IFSD (birdstrike, ashes, fuel exhaustion/contamination) are not the same than single IFSD (reliability), except maintenance. On the other hand, CFM states a CFM56-5B as an actual IFSD rate of 0.003 instead of the fleet-average 0.02 required for ETOPS 180.

You'd think there would simply be a list somewhere, of, all cases of both-engine-failure last year.

@Fattie: The last one was a   birdstrike in 2019, after two cases of fuel exhaustion in 2016 and 2012. Add to this a few avoidable other resulting from improper crew actions like shutting down the wrong engine after a single IFSD.

@mins it sounds like there are NO examples of plain "engine failure" as such

'deadstick_landing isn't necessarily fatal' ("with a glide ratio of 15:1, a Boeing 747-200 can glide for 150 kilometres (93 mi; 81 nmi) from a cruising altitude of 10,000 metres (33,000 ft).")

An aircraft cannot just stop in flight, like a car stopping on the roadside. Citation needed

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Why do turbo props have their engine controls like condition levers next to each other when other planes have them mixed up?
Comparing cockpits of the CRJ and the ATR. I noticed that turbo props have the throttle and condition lever next to each other. When the crj has just a throttle. and then some switches for fuel control. Why is this?

My understanding is that it is mostly a historical convention to make the turboprop engine controls resemble the spark-ignition piston engine controls that had mixture.
Turboprop engines usually have power, prop speed, and condition levers. Power should be obvious. Prop speed sets the prop speed as turboprops always have constant-speed propellers. And condition usually servers two functions: a fuel cutoff (which is what mixture is used for in spark-ignition piston engines), and switch between low and high idle.
Low idle is the minimum speed at which the engine will continue to run, but from that speed it is rather slow to accelerate when more power is commanded. So the high idle is a higher minimum speed from which the control response is considered adequate, to be used in flight.
The low/high idle could be just detents on the power lever, and that's what they are on jet (turbojet and turbofan) engines, when they are used and not completely automated based on weight-on-wheels sensor. And of course jets don't have any variable pitch propellers to control speed of, so all they have left is power and simple master and ignition switches.
Some turboprops have reduced the condition to a small lever or switch it can be, or merged the condition functions to the other two controls: combined cut-off with feather, and made ground/flight idle just the power lever detents. And some reduced even the prop lever to three positions: max rpm for take-off and landing, some pre-set lower value for economic cruise, and feather for if the engine fails.
Note that I specifically say spark-ignition. Compression-ignition, that is Diesel, piston engines don't have mixture control either. I don't know how the controls of the historical ones looked, but Diamond aircraft with Diesel engines don't have anything like condition, just engine master.

@Bianfable, almost all turboprops have FADEC these days, but the controls vary a bit.


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Can a free-falling aircraft with no horizontal (or minimal horizontal velocity) start up and fly to safety?
Inspired by this Grand Theft Auto gif, an aircraft with its engines initially idling is dropped from a high altitude (such as from the top of a building) with no or minimal horizontal velocity. Can it successfully throttle up and fly to safety? How about for

A fixed-wing aircraft, and
A helicopter

Forward or backward (like in the GIF?)

All the answers below are right, so this doesn't merit another answer. Still, it's really cool that Aviastroitel dropped a crewed glider from a balloon: https://www.youtube.com/watch?v=WSfMNEEnPoc

Rather obviously, both of these situations are far from likely to occur. As a result, the following is just idle (but hopefully informed!) speculation — I don't recommend experiments!

I'm going to be a little bit cheeky in answering this question -- you've asked if it's possible for “a fixed wing aircraft to [...] get the engines up to speed and fly off.” I'll answer “Yes, but it depends on the aircraft.” For the fixed wing aircraft I usually fly, a K-21 glider, getting the engines up to speed is a doddle — it’s powered by gravity (and essentially stays aloft by the sun). What matters here is the stall speed of the aircraft in question, and how quickly the pilot could recover from the ‘upset’ of being kicked off the top of a tall building, and land somewhere sensible (which can only realistically happen once the aircraft is not stalled). If the relative airflow over the K21’s wings is about 35 knots (40 mph, 65 kph) or greater, they generate enough lift to keep it airborne (and going about 30 m forward for every meter down).

If we assume that you’re a free-falling body, Newton (in the form of $v=u+at$) says that it’ll take about 1.8 seconds to reach that speed, and you’ll fall ($v^2=u^2+2as$) about 16 meters during that time.
Of course, you’ll be pointing nose down at the ground, accelerating, and needing to do something about it — which will take time, and, more importantly distance. But, in the grand scheme of sky-scrapers, mountains and cliffs, 16.2 m isn’t that high. Incidentally, for this reason, bungee launching is a traditional method of getting gliders airborne in parts of the world with big hills — a team of runners using glorified elastic bands shoot brave pilots into the blue yonder, as illustrated by the picture below (at the Long Mynd).

So, given that a hill is enough height for a sailplane to take off, possibly for a few hours on a good day, I’m reasonably sure that something like the John Hancock Centre would provide more than enough time for a pilot to recover from an odd attitude, loop forward to a nose-down dive, recover smoothly from it, and fly away (from the big building behind him).
The gif you linked to featured what looked a lot like a small private jet. I defer to the others on this site with a lot more turbofan experience than I, but I’ll just say this: given an hour that I spent in a 777 simulator, twenty minutes were spent going from “cold and dark” to pushback, I suspect you’d have a much harder time doing it. Of course, rapid engine starts are possible in some aircraft. It depends a lot on the exact circumstances you're asking (and passenger jets tend not to be designed for inverted flight, for example).

By all accounts, this situation isn’t probably going to be very recoverable. If the blades are stationary when the aircraft starts falling, they’ll be fully stalled, resulting in a low-rotor RPM stall, which, depending on the brand of helicopter may not “be recoverable” (e.g., even with a working engine, Robinson helicopters are generally not recoverable from a very low rotor RPM stall). Autorotation is the driven motion of the rotor by the air falling through it, but, as pointed out, fully-stalled blades at any angle will not generate much torque (or lift), and therefore be unable to arrest the rate of descent of the falling aircraft. I presume that the only exception would be a fuselage that could provide lift through another means, such as the V-22 Osprey.

The "brand" of helicopter does not matter. For any conventional helicopter that requires the rotor to be turning to generate lift, you will slam into the ground. Let's assume that you can stop the blades from folding upwards and let's assume that somehow you are lucky and the craft remains upright. The airflow is now entirely upwards through the disc and even with full collective applied, the AoA will be something greater than 90 degrees.  Even with a slightly negative pitch, which some helicopters can adopt, the AoA is never going to be recoverable.

...since you have no way of adjusting the attitude.

Autorotation actually can spin up a rotor as evidenced by autogyros. It just requires horizontal flow across the rotor, not vertical, so the helicopter would have to be pointing nose-down during the fall. However unlike fixed-wing aircraft it lacks control surfaces that could ensure that attitude.

In the planes I've flown (a single-engine turboprop and a twin turbofan), both took 20 seconds or more from the beginning of the airstart sequence to the availability of power (of course, if the engines are idling as in the question, then you would just need the airspeed to get lift and then pull up and add power

@SSumner You've only flown turbines?? You didn't learn in a piston? At any rate, you can get power much faster than that in a piston. Like, less than 2 seconds from when you switch the ignition to 'start' (not that you should do that, but you can.)

@reirab - I did fly 12 hours in a piston, but I remember none of it, and I don't think we learned airstart procedures. Good to know

@SSumner Ah, interesting. Just out of curiosity, was that military or civilian flight training?

@reirab - military

Also, airplanes are designed to tilt forwards at slow speeds, so zero airspeed mean nose straight down very fast.

A similar effect can also take place when you stall an aircraft to 0 knots in the air. It would just hang there for a second and then fall. As it falls, it gains speed and given there is enough altitude, it can fly/glide normally.

Re "atSSumner You've only flown turbines?? You didn't learn in a piston?..." reirab.  atSSumner "Ah, interesting. Just out of curiosity, was that military or civilian flight training?" – reirab.  atreirab - "military" --SSumner.  -- umm, obviously.  No one else learns (almost) excusively in turbines.

Unlike in a RC or a maple tree seed, recovering from zero-RPM rotor is not possible in a helicopter because the "driving region" of the rotor system can't produce enough rotation to generate lift in the "driven region."
In fact, once a heli rotor RPM is reduced below about 80%, it stops flying

I've upvoted your answer, but because it seems to confirm an older one with more details, I've accepted that one. Thank you for taking the time to write this.

Landak's "full stall" answer is just wrong.

Can you elaborate? I don't understand the difference between what both of you are saying.

Non-pilots have a hard time understanding what "stall" means, and even fixed-wing pilots don't understand rotor my wing stalls.

This is intriguing, but I don't understand what @rbp means by "driving region" vs "driven region". Anyone could fill in the blanks and flesh out this answer?

Blade stop autos can be done with model helicopters, proving it is theoretically possible. There are a few differences in a model helicopters rotor design that make it more likely, but here is a video showing it done.

 At 1:55 the blades are slowed to the point they are no longer spinning and the helicopter drops like a shot duck, until the operator reduces pitch enough to get them spinning again - without power.
You'd probably not be able to physically withstand the stresses, but I think it's technically possible.

Models can do a lot of things full-scale aircraft can't, because the scaling does not work linearly. In this case I suspect the difference is that model rotor has relatively lower moment to inertia compared to the aerodynamic forces than a full-scale craft.

Not really. The major differences between the model and full size rotor mechanics are the model has far more blade pitch movement (most models like that pictured have blade angle range close to 12 degrees plus and minus), and the rotor head on the model is far more stiff (which results in a less stable, less comfortable flight, but allows for more control). Both of these things make it easier to accomplish flight from a drop, but I still think it's theoretically possible. I doubt anybody will ever try it with a functional helicopter.

As long as you have enough altitude it's perfectly possible to pick up speed in a vertical or near-vertical dive in a fixed wing aircraft then convert that vertical speed into forward speed.
Red bull recently did a stunt where they landed a fixed wing plane on a skyscraper helipad and then took off again.
Since the helipad was small, the pilot wasn't able to gain much speed before leaving the helipad, so he dived picked up speed and then pulled out of the dive.

The plane was heavily customised for the stunt, a more normal plane would likely need substantially more altitude to acheive a similar feat.

In a fixed wing aircraft this is a common aerobatic maneuver called a tailslide.  Many airplanes can safely perform this maneuver, and if you google around, you can easily find video.


text:
Do airliners have horns for use on the ground?
When an airliner is on the ground, does it have a way of making a noise that can be heard by other people on the ground? Something like a car horn?

@mins But they still have to taxi in and out of areas where there are technicians, baggage handlers, ground vehicles, etc. Although I guess visibility wouldn't be much of an issue.

@isanae The solution to most of this is radios (like staying in touch with ground), having flashing lights and, well, just being a really big and loud jet.  The Gimlee glider was a special case, since the runway had been closed for quite some time, and was only being used because it was an emergency.

I realize that you asked about airliners, but the same question comes up for light aircraft, and some people have suggested carrying an air horn for use in the case of engine failure. There's at least one aviation-specific product.

@Pondlife I asked about airliners because I assumed smaller airplanes would have one. Apparently, I was wrong.

A horn would only be useful in a very specific scenario that should never happen anyway. There was a discussion on the AOPA members forums about this and most people thought it was pointless. Interestingly, glider pilots don't seem to carry them either. Of course, that scenario does come up sometimes (like the link I posted) but it's so rare that it's debatable if it's worth worrying about.

I have to disagree with the "without engines, it's silent".  Having lived near the approach end of a commercial airport, I can testify that even with the engines spooled all the way down, they make quite a bit of noise passing through the air.  Also, even when the engines spool up, you hear the majority of noise as they pass overhead and from behind, not as they approach.  (And interestingly, if air conditions are right, you can hear the wingtip vortices for a minute or two after the airliner passes - even after it has touched down, sometimes.)

@jamesqf I'd say in the case of a double engine flameout, a 767 side-slipping towards a runway at 500 feet is going to be pretty sneaky.

@isanae: But adding any reasonable sort of horn/siren to it isn't going to add much to the noise it already makes, just from passing through the air with gear & flaps extended.

@jamesqf My question isn't about making noise in the air, it's about making noise on the ground, which ymb1 has answered satisfactorily below.

YES, the signalling or warning system aboard an airline could be compared to a horn.
I have seen horns on the Airbus A320 and the Boeing 737 which is located on the overhead panel that the pilots use to alert ground crew. In some circles this button is referred to as GND and is used for ground communication.

Source: KLM Blog
If engineers on the ground want to contact the pilots in the cockpit they can do so via a button located in a little compartment near the nose wheel at the front of the aircraft. Thereafter,by plugging a headset into this compartment,they can communicate directly with the cockpit. However, not all certified aircraft have this warning system.
The horn is primarily a means of communication, but the aircraft itself can also emit a signal to warn engineers when a system breaks down or when there is fire

The KLM blog you linked has a "steamboat" sound and a siren, but I have trouble estimating their loudness. Are they both coming from the nose wheel to tell the engineer to put a headset on, as in ymb1's answer? Or is that something else?

@isanae In several aircraft there is a little compartment near the nose wheel at the front of the aircraft.Engineers on the ground plug a headset into this compartment in order to communicate with people in the cockpit. The horn is not very loud because it's just a way for the cockpit to gain the attention of ground staff.

I understand that. I just wanted to confirm that the "steamboat" sound was also a ground call horn for the engineer, or something different. It appears your answer is very similar to ymb1's.


text:
Why is the refueling point of this A320 on the left wing instead of the right?
Every other A320 I've seen has the refueling done in the right wing but not this one. Why?
Registration YL-LDN

I was looking at the plane for some words, and there are none so its possible the photo was flipped horizontally.  Then I saw the "AirBP" wording on the fuel bowser so its just a blank paint job, possibly brand new or at least being re-painted.

@Criggie The fuel truck has "air BP" written on it, therefore if the the photo initially contained both the aircraft and the truck, it's definitely not flipped.


text:
How many checklists are there for a commercial pilot for the entire flight?
I wanted to know the number of times a pilot has to refer to his/her checklist for the entire flight (before startup to engine shutdown).

Typically, the checklists in normal operations are:

External walk around and preflight
Before start
Before taxi
Before take-off
After take-off
Cruise
Descent
Approach
Landing
Shutdown
Secure

This list is pretty much the same for all aircraft.
Normally, each checklist is only used once at the appropriate time but a wise pilot would re-run a checklist if interrrupted.
For example, you are cleared to start and complete the before start checklist but there is then an unexpected delay before you actually start.  You wait for 30 minutes.  No need to redo the before start checklist because you did it earlier?  No, do it again.  Something might have changed.

That is 10; in my operation there are 8 on a normal flight, or more if deicing is required. Eight to ten is probably a fairly normal range for most operations.

@RalphJ Thanks Ralph.  Is it accurate to say that some are either rolled into one (i.e. shutdown and secure) or simply not required?  I fly one type which doesn't even have a written checklist for descent but there is a "memory" item which is carb heat as required.

Many jets also have taxi, lineup, transition level, cruise, before landing, and after landing checks too.

@Lnafziger Almost all jets have an extra pilot to run them all, too!

@rbp Yes, and the question is tagged "commercial-aviation".  :)

Simon mentioned a great list of common checklists (of course, keep in mind there are lots of other checklists for emergency situations; fuel dump, engine out, engine fire, hydraulics, etc. etc.)- I would like to address one specific point in your question:

I wanted to know the number of times a pilot has to refer to his/her checklist

I don't mean to be pedantic here, but checklists are always referred to (in other words, they are not memorized). Even the most experienced pilots go through the checklist manually  - of course - it takes them quicker to go through each checklist due to their experience but they always refer to it.
I have the most experience with the 737 and on this aircraft, typically the checklists are laminated and on some aircraft placed above the cockpit instrument cluster; in addition some checklists are actually written on the yoke itself:

(image from wikipedia entry on yoke)
The checklists are before takeoff / after takeoff / approach / landing. The little yellow bug (on the right) is to keep track of the items.
During one of my orientation sessions, the instructor reminded me to not do the checklist by memory, you must always refer to the written list.
He then mentioned "in the air force they make us memorize the checklists and do them by memory, but not on civilian aircraft".

There was a fatal accident a bit over a year ago at a small airport near me that was caused, in large part, because the pilots didn't go through any of their checklists. They had forgotten to disengage the gust lock.


text:
How do test pilots determine an aircraft's capabilities?
How do test pilots figure out an aircraft's capabilities (service ceiling, cruising altitude, etc.)? Do they simply take the plane to its limits to get that information?

Short:  The pilot has a well-defined range of discretion within progressively increasing bounds very tightly set as part of a structured development program aimed at eliciting maximum information regarding actual versus theoretical flight envelope in all conceivable modes and situations.
Longer: A test pilot's main task is to carry out a progressive program of tests aimed at investigating the correspondence between designed and actual capabilities, and identification of any unexpected variations from nominal which occur along the way. The designers know everything they consider the aircraft should do and shouldn't do and should be able to do long before it first flies. The job of the test pilots is to find out the places where the designers are wrong by carrying out an extremely well planned program while applying her or his skill to come back alive when the designers and/or manufacturers get it wrong.
The pilot will usually have input into the process of deciding the rate which the program is carried out, how large progressive steps are and attempting to anticipate in advance what is likely to be viable or problematic. Their feedback along the way will help inform decisions about modifying program objectives or rate of implementation or lead to modification to the aircraft. A highly skilled test pilot is a member of a synergistic team and while program decisions are the responsibility of the 'project manager' (or equivalent) it is likely that what the pilot says and wants will be close to indistinguishable from what actually is done.
However, the actual program on a given occasion is not the pilot's responsibility and limits on what are attempted or implemented are well-defined in advance. The pilot will be given discretion in advance regarding ranges of parameters which may be investigated, e.g., closeness of initial approach to Mach 1, rate of ascent or g forces applicable in various modes*. And the safety of the aircraft first and the pilot second (in many cases) is left to the pilot's discretion BUT subject to substantial guidance, e.g., 'bringing the aircraft back intact' is often going to provide far more information when a problem occurs so a pilot may make every effort to do so in situations where an ejection may otherwise be preferred. A  pilot who ejects more than most may or may not be criticized for any given decision but is less likely to be given as many chances in the future to risk their life even more than before. However, a pilot who crashes fatally while trying to save an out of control situation will in the future only take part as the subject in training videos and in establishing "see if you could have handled this one" simulation scenarios.
Striking the right balance between these two 'modes' is what makes a great test pilot. But they still don't just get to go out and "see what it can do".

A well judged ejection occasion - genuine.
From here
English Electric Lightning early testing.  Prior ejection would very likely have been justifiable but is unlikely to have been considered. The pilot (George Aird) survived with relatively minor fractures - in part caused by descending through the roof of a glasshouse :-). Pilot was on final for an emergency landing as a fire was attacking the rudder actuator. At 100 feet altitude and 10 seconds from touchdown, Murphy won, the actuator support burned through and the plane pitched nose down. Go!

Glasshouse with pilot and ejector seat entry points (side by side) ringed in red. Canopy caused damage at far end.
The remains of the aircraft can be seen in a very small area just inside the airfield boundary.

Photographers are lucky to get one opportunity like this in a lifetime.
I'm still waiting :-)

What do I know?: Layman. Engineer. Non pilot. Read too many test-pilot autobiographies. The ones you read tend to be from those who are good and didn't die.

I was recently rererereading Roland Beaumont's "Phoenix into Ashes" - an  account from the leading test-pilot of many (most) of the early British jet aircraft. He recounted the loss of a test aircraft while pulling 9g (as I recall) in a situation which should have been inside the design envelope. The pilot died. The observer lived to provide 'human black box' functionality. It was established that fuel transfer protocols were not correctly followed, leading to over-stressing part of the airframe and thus fatal loss of control, i.e., "just" mishandling fuel tank sequencing may kill you. Nowadays computers will tend to stop this sort of error. But Murphy has many alternatives.


text:
What's the EPNdB for large turbofan engines for stage 5 noise regulations?
I'm trying to estimate the Effective Perceived Noise (EPNdB) of the GE9x. GE Aviation says that it will be within 8 dB margin of the stage 5 noise regulations, can anyone confirm that?

What the FAA is calling "Stage 5" is the ICAO Chapter 14 regulations. These do no go into effect until 2017 or 2020, but that means it would be applicable for future engines such as the GE9X.
The cumulative EPNdB margin for Chapter 14 is Chapter 4 +7, or Chapter 3 +17. The exact EPNdB value depends on takeoff weight.

Thank you, I found document to be helpful as well. http://www.icao.int/Meetings/Green/Documents/day%201pdf/session%202/2-Dickson.pdf


text:
For the CFIs, CFIIs, MEIs, and AGIs - How often do you find students that utilize your ratings?
I am curious. Out of 100 new students that walk into the average flight school, how many only need a standard CFI, how many do instrument training, and how many do multi-engine training? Additionally, how much work does an AGI get? I’m trying to compare the cost of these ratings against how often they will be utilized.
Also, for the sake of data that makes some kind of sense, let’s exclude the recent Covid-19 market activity and go with pre-February 2020 numbers.

AGI and IGI test you on the same knowledge that you need for CFI and CFII. There are a few questions on helicopter operation but you can miss those and still pass or spend a couple of interesting hours reviewing FAA books. Cost of these is just the cost of the three tests and some study time. I’ve never earned money from mine so I can’t comment on the demand for ground instructors.

Forgot to add,  If you don’t live near a FSDO, you’ll need to add in the cost of flyng there to do the paperwork required to get your certificate.

@JScarry, what you just said aid is basically the issue in a nutshell. AGI and IGI may only cost a few hundred dollars, but if you’ve never gotten any work from them, maybe the money is better spent elsewhere.

@AaronHolmes for most people, their main motivator for obtaining a ground instructor cert is that it's a prerequisite for a Gold Seal.  Other than that, it could be used by those who lose their privilege to fly for medical issues so they become full-time ground instructors.

I added the USA tag since this seems to be a US-focused question. If I'm wrong about that, don't hesitate to change the tags and/or edit your questions. Please remember that this is not a US-only site, and we strongly prefer questions to identify the country or regulations they're asking about. If that's relevant to the question, of course!

First off, it depends on what kind of flying you want to do.  Remember a flight instructor certificate is not required to fly an aircraft, either personally or professionally.  The problem comes in that most professional flight jobs, either under part 121 or 135 require over 1000 hours total flight time and in some cases over 1500 hours TT.  For a budding pilot with no other sources of income, this becomes almost insurmountable without doing flight instruction, as you’re legal to do this with 250 hours TT, a CPL, INST-A, and a CFI.  If you do go the instructor route, the ratings you get for a flight instructor certificate all depend on what you’re going to do as an instructor. Instructor pay is based upon 1) the number of ratings that you have and 2) your dual given time.  Remember, the more ratings you have the more flexible your employment options are; CFIs with 152/172 time are a dime a dozen.  MEIs command the greatest salaries, though some schools only pay top dollar for multi engine dual instruction hours.  Many schools today won’t employ you without at least a CFII (welcome to the insanity of flying for a living!).  As to AGIs or IGIs, it again depends on the size of the flight school and the number of ground courses being offered.  You can also do this as an independent contractor, but you will also have to recruit clientele, this is work in and of itself.  Large Part 141 flight schools may have dedicated ground instructors for ground school, or may simply require new hire CFIs to hold ground instructor ratings.  Ground instructor ratings are relatively easy to obtain; some home study followed by a testing fee of $300 or so for both the FI and AGI will get you one.  Typical ground instructor pay is lower, on average, than flight instructor pay, but it all depends on your ratings and experience.
If you’re interested in making money as a CFI, my advice is to specialize.  As I said before a CFI with dual time in Cessnas is so common that it doesn’t command much in pay in and of itself.  Someone who can do, say, multi-engine, tailwheel, basic and advanced aerobatic training, CSIP certified, type ratings, seaplane rated, mountain flight training, warbirds, helicopters, gyroplanes, etc. can command over six figures as a CFI.  The downside is that obtaining these additional ratings will cost hundreds of thousands of dollars so entry becomes prohibitive.
Now as to the numbers of people who become pilots and then flight instructors vs come through the door with an interest in flying, I’m not sure but I’d venture a guess that around 75% won’t even solo.  Most people take a general interest in learning to fly then quit after a few flights from 1) the cost and time required to train, 2) medical or other barriers which prevent them from pursuing flight training and 3) the difficulty of flight training - many people expect something similar to the standards of US Driver’s Education or an MSF basic rider course and become disenchanted with flying when they can’t learn in a weekend by reading a 40 page booklet with a few flights.  In the United States there are only about 600,000 licensed Pilots in a country of 300 million.  Doing the math this works out to be about 1 in 500 people hold a Pilot certificate.  Pilots holding instrument ratings are around half of the total ie about 300,000.  Commercial, and Airline Transport Pilots - professional people who fly for a living - are around 100,000 and there are about 100,000 active flight instructors in the US as well.  You can check the FAA’s Airmen Statistics for more precise figures.  So if we go by the numbers of students at a typical flight school, out of 100 new people off the street, on average, only 25 will become licensed pilots.  Of those 25, 12 will get instrument ratings and 6 will go onto obtain commercial certificates and flight instructor ratings.

The words "pyramid scheme" comes to mind.

I wouldn’t call it a pyramid scheme per se; more of a supply and demand thing.


text:
Has an unauthorized civilian ever tried to land on an aircraft carrier?
Has there ever been an attempt by a civilian 'daredevil' to land a plane on a US aircraft carrier?
I came across the Red Square Landing and coupled with this video it made me wonder if there was ever a civilian who attempted - illegally, of course - to land a plane on a carrier?

Before landing the pilot would have to find the carrier, and to fly the distance, which could be itself a challenge. Moscow is on land.

@mins: "Moscow is on land"  [citation needed]

I'm not exactly sure whether this counts, but I think the landing of South Vietnamese Air Force Major Buang-Ly on USS midway using a Cessna O-1 Bird_Dog comes pretty close.
Though Major Buang-Ly was not a civilian, he has never seen a carrier before and the landing wasn't exactly illegal. It was permitted by Captain Larry Chambers during Operation Frequent Wind, who even scuttled helicopters on the deck to ensure safe landing.
The image below shows the aircraft as it comes to a stop.

Image from forum.worldofwarships.com


text:
Do real aircraft have something close to the GPS/NAV modes in FSX?
I am a long-time flight simulator player and also very interested in aviation. In FSX, all aircraft have a GPS/NAV knob which allows the pilot to switch between direct GPS autopilot and VOR navigation Autopilot. However, when I look at the main panel of a real Boeing cockpit, I don't see a GPS knob but I do see NAV V and NAV L buttons.
I know what NAV V and NAV L are (V for vertical autopilot, and L is the same as the NAV mode in FSX that keeps the plane on course), but do real aircraft (specially Boeing) have any function to keep the aircraft automatically on course and direct it toward the destination without using a VOR? Something that works very much like the GPS mode in FSX?
And in FSX I have to manually set the VOR frequency based on the navigation chart, in real life do the pilots have to do the same, or do they have some more advanced features?

Most real airliners have flight management systems which can be set to automatically direct the autopilot to fly the route programmed into the FMS before departure.

@reirab: So you mean that does exist in real aircrafts? and what is ADF? is it the same as what you explained?

An ADF is an Automatic Direction Finder.  In its most common form it merely points an arrow on a compass card in the direction of an AM radio station or at a "NDB" (Non-directional Radiobeacon).  Now considered primitive even obsolete in today's cockpits, the system of NDB/ADFs was a primary means of radio navigation for many years, and is still in wide use overseas, particularly in third world countries.  There are still some approaches in the US that depend on the good old ADF - although a modern GPS can substitue for them.  Many use them to listen to ball games on cross country flights.

In the Boeing world, LNAV is Lateral Navigation, and VNAV is Vertical Navigation.
When LNAV is engaged, the autopilot will follow the Flight Management Computer (FMC) guidance laterally, i.e. left & right.  When VNAV is engaged, the autopilot will follow the FMC guidance vertically, i.e. climbs & descents.
LNAV is conceptually pretty simple: you have a magenta line on the map, your desired course, and the autopilot will follow it.  The points defining your course are database points in the FMC that may but certainly do not have to correspond with VOR's or other conventional NavAids.  You can use LNAV to fly VOR-to-VOR, or it can fly point-to-point-to-point equally easily.  (You don't have to tune any frequencies in either case.)
VNAV is a little more complicated, because you may only be cleared for some of what the FMC wants to do vertically.  Simple example: you're cruising at FL370, planning to start down at a given point so as to cross AAA at FL240, and then continue the descent to cross BBB and 10,000' and 250 knots.  ATC clears you to "descend at pilot discretion, maintain FL 290."  That means you can start down at whatever point you want, but until you get cleared lower later on, you can't descend all the way to FL240 or 10,000.  Yet.  Or maybe the controller needs to put you at FL350 right now to avoid a traffic conflict 100 miles ahead, and your clearance is "descend now and maintain FL350, pilot discretion FL290."
It's a lengthy section of Ground School how the pilot sets up the FMC and the mode control panel to accomplish all of this, but hopefully that illustrates some of the complexity of VNAV.
It's a good system; under typical conditions you can go into LNAV and VNAV shortly after takeoff and stay in them both until shortly before landing, and the FMC gives you smooth (mostly) and efficient guidance.

Thank you very much indeed, you actually explained it all the best possible way.

LNAV and VNAV are not exclusive to Boeing/Airbus/airliners. I've flown G1000-equipped Cessnas and Columbias with the ability to have the AP handle LNAV and VNAV. It's simply FMS terminology.

It should be added that the LNAV is a "GPS" mode except the FMC  combines INS, GPS and VOR/DME input to determine the current position. A pure VOR/ILS mode is still available (and mainly used for ILS).


text:
What happened to the Fokker 100 revival project?
What happened to the Fokker 100 revival project by NG Aircraft?
They wanted to build a better Fokker 100 called the Fokker 120NG/Fokker 130 in 2010-2014 which originally should be completed this year.

NG Aircraft still exists, or at least, they still have a website. The big roadblock is financing the development of the aircraft. I did a search in Dutch government records: the most recent mention is in 2016, indicating that at that time sufficient funding has not been found yet to start development in earnest.
LinkedIn shows 11 employees.

Thanks for the great answer and your research


text:
Can I do an IFR checkride in an airplane that isn't certified for IMC?
Related to Can a plane be IFR certified, but not allowed in IMC? and Are there any LSA aircraft that can be flown IFR in IMC? .  I understand the distinction between IFR and IMC.  I can train for IFR in such an airplane in non-IMC conditions, but I cannot fly in actual IMC.
Does this mean that I can take my IFR checkride in such an airplane, too?

It looks like your question is already answered in the first question you linked to. It quotes an FAA document on instruction and checkrides. Can you clarify what is different about your question?

clarification: checkride not just training.

Yes, the document says "instrument flight training and/or airman certification testing".

Legally, you can take your instrument rating checkride (not "IFR checkride") in an airplane that is not equipped for flight under instrument flight rules. That is because you will fly your check ride under VFR. As I did. The examiner will act as "safety pilot," a require crew member, while you are the sole manipulator of the controls under SIMULATED IMC via the view limiting device. The examiner will ask you to do the required tasks, and you will coordinate the tasks needing ATC assistance with ATC, who will remind you to "remain VFR" while you are on practice instrument approaches and so on. You cannot fly the checkride under instrument flight rules because you don't have an instrument rating. The examiner won't (or at least most won't) file an IFR flight plan as PIC using his/her rating.
But that's legal. In practical terms, at least in my opinion, any examiner is going to be reluctant, or at least suspicious, of a request for an applicant to complete the instrument rating checkride in an airplane not fully equipped for instrument flight. In particular, he or she is going to insist that the airplane be equipped for several different types of instrument approaches. My understanding is that it's up to the examiner, so check in advance if your examiner is comfortable using the airplane that you propose to use.

Welcome to aviation.SE!

I would train in an LSA that is IFR equipped, but not legal in IMC .  If even VFR airplanes can do this, then it presumably means that LSA "IFR equipped in non-IMC permitted aircraft" are good for the instrument rating checkride.  your answer goes further, but leads me to believe that I should be ok in this scenario without difficulty.

You are most certainly wrong. In most cases, the IR checkride will take place in VMC under VFR, however, the examiner can and will file and fly IFR, acting as PIC, for the checkride if there are clouds present that must be flown into to complete the approaches.

PilotDan: When I took my IR checkride, the examiner insisted on an VMC day and made it his particular practice to do all his checkrides in VMC under VFR only. We had to wait for good weather to do the IR checkride. No doubt about what happened with your examiner, and that certainly is allowed. It is up to the examiner whether he wants to act as PIC and file and fly under IFR. Your examiner did; my examiner didn't. I'm not sure we have enough data to say "most do" or "most don't".

There are lots of reasons that an IFR certified aircraft may not be legal to fly in IMC. An airplane must have had an altimeter and pitot/static check within the last 24 months. If using VORs for navigation, a VOR check is required within 30 days. If you are planning on using GPS approaches or departures, then your database must be current.
Since you start off your checkride by filing and flying an IFR flight plan, then it you would need an airplane that is currently capable of IFR flight. However, the current PTS does not require that an actual ATC clearance be received:

III. AREA OF OPERATION: AIR TRAFFIC CONTROL CLEARANCES AND PROCEDURES
NOTE: The ATC clearance may be an actual or simulated ATC clearance
  based upon the flight plan.

If your designated examiner agrees beforehand that you will use a simulated clearance, then you would not need an IFR certified airplane. Otherwise I believe you would.
From the FARs:

§91.205   Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.
  (d) Instrument flight rules.
(1) Instruments and equipment specified in paragraph (b) of this section, and, for night flight, instruments and equipment specified in paragraph (c) of this section.
§91.411   Altimeter system and altitude reporting equipment tests and inspections.
  (a) No person may operate an airplane, or helicopter, in controlled airspace under IFR unless—
(1) Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter;

(Emphasis added)
And from the Instrument Practical Test Standards (FAA-S-8081-4E PTS Instrument)

Aircraft and Equipment Required for the Practical Test
  The instrument rating applicant is required by 14 CFR part 61 to provide an airworthy, certificated aircraft for use during the practical test.
Its operating limitations must not prohibit the TASKS required on the
  practical test. Flight instruments are those required for controlling
  the aircraft without outside references. The required radio equipment
  is that which is necessary for communications with air traffic control
  (ATC), and for the performance of two of the following nonprecision
  approaches: very high frequency omnidirectional range (VOR),
  nondirectional beacon (NDB), global positioning system (GPS) without
  vertical guidance, localizer (LOC), localizer-type directional aid
  (LDA), simplified directional facility (SDF), or area navigation
  (RNAV) and one precision approach: instrument landing system (ILS),
  GNSS landing system (GLS), localizer performance with vertical
  guidance (LPV) or microwave landing system (MLS).
GPS equipment must be instrument flight rules (IFR) certified and contain the current database.

(Emphasis added)
Training is a different issue since, except for your cross-countries, you do not need to file an IFR flight plan to practice approaches and navigation solely by reference to instruments.

Regarding the checkride, the regs quoted in the referenced question seems to indicate otherwise -- that the checkride can be taken in VMC in an aircraft used to train in VMC. Any thoughts on that?

[1] does a checkride need to file a real IFR flight plane??  how?  legally, I can't file IFR as PIC until after the ride!!  (we reasonably need to fly one on the checkride, but do we need to file one?!)  [2] my issue is not the pitot/altimeter check, but (primarily) the Rotax engine, so 91.411 should not bite me.   either of these would suggest that this specific issue should not be a hurdle, but I am not certain.

It was a while ago, but if I recall correctly, on my IFR checkride I filed an IFR flight plan and opened it. We flew the departure then cancelled. Just like on my Private checkride where we filed a VFR flight plan then cancelled it after the first or second checkpoint.

@ivoWelch The current PTS does not require that an IFR flight plan be activated so I updated my answer.

Uggghhh...this raises a new question: does to provide an airworthy, certificated aircraft mean that checkrides cannot be done in experimental IFR equipped aircraft, like Vans?

I took my Rotorcraft IFR checkride in a helicopter not approved for IMC flight.

@ivoWelch An IR checkride can be done under IFR if the DPE acts as PIC. That may happen if the day of your checkride is cloudy and the DPE doesn’t want to reschedule.

@StephenS The FAA really discourages taking an IFR checkride in IMC. My checkride was postponed after the oral because of clouds on both ends of the runway. Weather was marginal when I did the flight portion and I flubbed the exit from the hold to the ILS so had to do that over again. After multiple reschedules for weather on the last possible day to do the retest there was a cloud bank over the approach and the DPE had me request a pop-up IFR approach.

@JScarry They can “discourage” the practice, but unless they ban it, it’s worth asking the DPE if it comes up.


text:
Where can I listen online to live VOLMET broadcasts?
Are there sites that stream live VOLMET broadcasts? I need to listen to the format but haven't have the time to put together an amateur radio.

Does it have to be live? There are plenty of recordings on Youtube

Good to be live, esp when you want to know how to pronounce different airport codes

The airport names are pronounced in full in a VOLMET (not just their code). As are weather phenomena. Letters and numbers are pronounced exactly as normal (phonetic alphabeat). Still not sure what difference it makes to you if it's a live broadcast or not.

https://www.youtube.com/watch?v=iX_3XT_hQZU

The Globaltuners site will allow you to tune their UK radios (subject to them being online) to the UK VOLMET frequencies if you really wanted. Whether this is technically "legal" or not is for you to decide ... it's not in the UK, but it's not enforced either.


text:
May an A330 depart with with empty outer fuel tanks?
Airbus does not recommend flying with empty outer tanks, to reduce stress on the wings. Also, when the outer tank transfer valve is inoperative, the MEL says to fill the outer tanks with fuel and it will all be unusable during flight.
Otherwise, I couldn't find a specific restriction anywhere about departing with empty outer tanks. Is it acceptable or not?

Can you explain what kind of answers you are looking for? You already know what Airbus think about this issue, and why.

Don't know the system at all, but it sounds like if you fill inner tanks only, the xfer system will automatically move fuel to the outer tanks to move the fuel mass outboard, but if inop it can't do this so you have to fill them for ballast.  If it was that big  a deal, there must be an Operating Limitation in the AFM.

@DeepSpace some answer that I couldn't find out. I read it as a recommendation but thinking about MEL, maybe it is mandatory

@John K there is no such automatic system . thanks

The MMEL instruction is mandatory if you want to dispatch using that relief (I'm assuming it says "fill the outer tanks", not "recommended to fill the outer tanks"), but where the instruction has to be followed as opposed to recommended, I would've expected to find an Operating Limitation associated with it.


text:
Where can I find the various operating limitations of the ATR 72-500?
Where can I find the various operating limitations of the ATR 72-500? Is there any document that lists them?

Are you talking about Limitations? If yes, that information is in POH/AIM.

YES, i am looking for limitations, can i get any documents other than flight manual?

LIMITATIONS
PAGE : 001 APR 11 EASA APPROVED
Model : 212 A
  AFM 1

2.01.01 | INTRODUCTION
Observance of the limitations contained in this chapter is required by law. When
  operating in accordance with an approved appendix or supplement to
  this manual, the limitations of this basic Airplane Flight Manual
  section apply, except as altered by such an appendix or supplement.
2.01.02 | KINDS OF OPERATION
The airplane is certified in the
  Transport Category, JAR 25 and ICAO annex 16 for day and night
  operations, in the following conditions when the appropriate equipment
  and instruments required by the airworthiness and operating
  regulations are approved, installed and in an operable condition :

VFR and IFR
Flight in icing conditions.
Reverse thrust taxi (single or twin engine)

2.01.03 | MINIMUM FLIGHT CREW
2 pilots
2.01.04 | PERFORMANCE CONFIGURATION
Refer to 6.01.03 for airplane configuration associated with certified
  performances.
2.01.05 | MAXIMUM OPERATING ALTITUDE
25000 ft
2.01.06 | MANEUVERING LIMIT LOAD FACTORS

Gear and flaps retracted : + 2.5 to -- 1 g
Gear and/or flaps extended : + 2 to 0 g

2.01.07 | CONFIGURATION DEVIATION LIST
Refer to 7.01.02
2.01.08 | NOISE CHARACTERISTICS
The aircraft meets the requirements of ICAO annex 16,
  Chapter 4 with no weight restriction. Refer to noise characteristics
  in Appendix 7.01.01 of this manual for noise levels.
2.01.09 | MAXIMUM NUMBER OF PASSENGER SEATS
74 as limited by emergency exits
  configuration
2.02.01 | WEIGHTS
STRUCTURAL LIMITATIONS
MAXIMUM WEIGHT KG LB

RAMP 22970 50640
TAKE-OFF 22800 50265
LANDING 22350 49273
ZERO FUEL 20800 45856

PERFORMANCE LIMITATIONS
Maximum take-off weight and maximum landing weight may be reduced by performance
  requirements related to the following (see chapter 6) :

climb performance (first and second segment, final take-off and en route, approach and landing climb)
available runway length (take-off and landing)
tyre limit speed
brake energy limit, observe BRK TEMP alert for take-off
obstacle clearance (take-off and en route)
en route and landing weight

2.03.01 | AIRSPEEDS

MAXIMUM OPERATING SPEED VMO / MMO
This limit must not be intentionally exceeded in any flight regime.

VMO = 250 kt CAS
MMO = 0.55

MAXIMUM DESIGN MANEUVERING SPEED VA
Full application of roll and yaw controls, as well as maneuvers that involve angles of attack near the stall
  should be confined to speeds below VA.

VA = 175 kt CAS

CAUTION: Rapidly alternating large rudder applications in combination with
  large sideslip angles may result in structural failure at any speed.
MAXIMUM FLAPS EXTENDED OR OPERATING SPEEDS VFE

FLAPS 15 185 kt CAS
FLAPS 30 150 kt CAS

MAXIMUM LANDING GEAR EXTENDED OR OPERATING SPEEDS

VLE = 185 kt CAS
VLO
lowering = 170 kt CAS
retracting = 160 kt CAS

2.03.02 | OPERATIONAL PARAMETERS ENVIRONMENTAL ENVELOPE
Note : Refer
  to 2.04.05 for fuel temperature limitation. TAKE–OFF AND LANDING –
  Tail wind limit : 15 kt – Maximum mean runway slope : ±2 %
2.04.01 | ENGINES
PRATT&WHITNEY CANADA PW127F or PW127M or PW127N
Operating limits with no unscheduled maintenance action required;
  Beyond these limits refer to maintenance manual.
OPERATING CONDITION TIME LIMIT TQ
  (%) ITT ($^\circ$C) NH (%) NL (%) NP (%) OIL PRESS (PSI) OIL TEMP ($^\circ$C)
  (2)
RESERVE TAKE OFF 10 mn (6) 100 (1) 800 103.2 104.2 101 55 to 65 0 to 125
NORMAL TAKE OFF 5 mn 90 (1) (5)
  101.9 101.4 101 55 to 65 0 to 125
MAXIMUM CONTINUOUS none (7)
  90.9 (1) 800 103.2 104.2 101 55 to 65 0 to 125
GROUND IDLE 66 mini 40 mini (4)
  -- 40 to 125
HOTEL MODE 715 55 to 65 125
TRANSIENT 20 s 120 840 106.4 106.8 106 (3) 40 to 100 5 s 120 20 mn 140
STARTING 5 s 950 --54 mini

Value linked to 100 % NP.
Oil temperature must be maintained above 45$^\circ$C to ensure protection for
  the engine air inlet against ice accumulation.
Permissible for completion of flight provided TQ does not exceed 75.2 %
  during climb and 73.13 % during cruise.
Up to 75 % NH only.
ITT limits depend on outside air temperature. Refer to 2.04 page 2.
Single engine operation only, beyond 5 mn.
MCT rating is the max
  power certified for continuous use. In-flight emergencies are the
  only conditions for which MCT use is authorized.

NOTE : Flight with an
  engine running and the propeller feathered is not permitted
2.04.02 | PROPELLERS
TWO HAMILTON STANDARD HS 568 F
   – 1 GROUND OPERATION
  Engine run up must be performed into the wind.  Avoid static operation
  between 41.6 % and 62.5 % NP.  Avoid operation in feather above 66.6 %
  TQ.
GROUND OR FLIGHT OPERATION  If a propeller is involved in an
  overspeed or in an engine overtorque refer to the propeller
  maintenance manual.
FLIGHT OPERATION  ATR airplanes are protected
  against a positioning of power levers below the flight idle stop in
  flight by an IDLE GATE device.  It is reminded that any attempt to
  override this protection is prohibited. Such positioning may lead to
  loss of airplane control or may result in an engine overspeed
  condition and consequent loss of engine power.
04 POWER PLANT 2
  LIMITATIONS PAGE : 001 DEC 96 EASA APPROVED
  --Model : 212 A AFM 4 AUG 07 FEB 05 R JUL 06 SEP 06 R R R
2.04.03 | OILSYSTEM SPECIFICATION Refer to specification PWA 521 type II.
2.04.04 | STARTER
3 starts with a 1 minute 30 seconds maximum combined starter running time followed by 4 minutes OFF.
2.04.05 | FUELSYSTEM
Acceptable fuels : Jet A, Jet A1, JP5 and RT, TS1. Use of JP4 and Jet B is prohibited.
TEMPERATURE

For flight
  preparation, a minimum fuel temperature must be taken into account to
  ensure adequate relight :

3 4 o C JET A, JET A1 and RT, TS1.
2 6 o C for fuel type JP5. •Maximum temperature : 57 o C for fuel types JET A, JET A1, JP 5 and RT, TS1.

REFUELING
Maximum pressure 3.5
  bars (50 PSI)
USABLE FUEL
The total quantity of fuel usable in each
  tank is : 2500 kg (5510 lbs)
NOTE :Fuel remaining in the tanks when
  quantity indicators show zero is not usable in flight.
UNBALANCE
Maximum fuel unbalance : 730 kg (1609 lbs)
FEEDING

Each electrical pump is able to supply one engine in the whole flight envelope.
One electrical pump and associated jet pump are able to supply both
  engines in the whole flight envelope

2.05.01 | AIR PRESSURIZATION

Maximum differential pressure: 6.35 PSI
Maximum negative differential pressure 0.5 PSI
Maximum differential pressure for landing 0.35 PSI
Maximum differential pressure for OVBD VALVE full open selection 1 PSI
Maximum altitude for one bleed off operation 20000 ft

2.05.02 | HYDRAULIC SYSTEM
All hydraulic fluids compliant with technical
  specification : NSA 307110 Compliant fluids are listed in the AMM
  (Chapter20, 20-31-30)
2.05.03 | LANDING GEAR

Do not perform pivoting (sharp turns) upon a landing gear with fully braked wheels except in case of emergency.
In case of ground speed over 165 kt all tires to be replaced.
Towbarless Towing is prohibited, unless the towbarless towing operations are performed in compliance with the appropriate
  operational requirements (JAR--OPS--1 for Commercial Air
  Transportation) using towbarless towing vehicles that are designed and
  operated to preclude damage to the aeroplane nose wheel steering
  system or which provide a reliable and unmistakable warning when
  damage to the steering system may have occurred. Towbarless towing
  vehicles that are specifically accepted for ATR aircraft are listed in
  ATR Service Letter 72--09--6001.

2.05.04 | FLAPS
Holding with any flaps extended is prohibited in icing conditions (except for single engine operations).
2.05.05 | AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

Minimum height for autopilot engagement on take off : 100 ft
NAV mode for VOR approach, using either autopilot or flight director is authorized only if :

a co--located DME is available, and
DME HOLD is not selected

Minimum height for use of either autopilot or flight director :

Except during take off or executing an approach : 1000 ft
VS or IAS mode during approach : 160 ft
CAT 1 APP mode : 160 ft Refer to 7.01.03 for CAT II operation

2.05.06 | INSTRUMENTS MARKING
Red arc or radial line : minimum and maximum limits Yellow arc : caution area Green arc : normal area
2.05.07 | CARGO DOOR OPERATION
Do not operate cargo door with a lateral wind component of more than 45 kt.
.../... 05 SYSTEMS 2 LIMITATIONS PAGE : 001 AUG 14 EASA APPROVED
  --Model : 212 A AFM 2
2.05.08 | ELECTRICAL
Single DC GEN operation : In flight, if OAT exceeds ISA + 25, flight level must be limited to FL200.
2.05.09 | MFC
Take off with two or more failed MFC modules is prohibited
2.05.10 | COMMUNICATIONS
Not applicable
2.05.11 | TCAS
When installed, Refer to appendix 7.01.0

Hello QWERTY, welcome to aviation.SE! That is a lot of text... could you improve the layout?

Can you add appropriate citation of the source? Preferably with link if it is available on internet.


text:
Do small helicopters like the R44 require an FAA type rating?
From what I read in 14 CFR 61.31 it never mentions type rating requirements for rotorcraft or helicopters. I Googled online but most of the results showed up for Australia, Canada and the UK.
I am starting to believe that the US does not require a pilot to have a type rating for a Robinson R22 or R44 helicopter.
Am I correct that unless the FAA has made a type certificate for that helicopter it does not require a type rating? Would it just require a checkout from wherever you are going to rent?

Keep in mind that many pilots will spend their very first rotorcraft hours in a R22...

From Wikipedia's article on the R22: "Due to the issues relating to a low inertia rotor-system and a teetering main rotor, operation by any pilot in the United States of the Robinson R22 or Robinson R44 requires a special endorsement by a certified flight instructor."

Pls correct me i am confused. Type certificate is for aircraft to operate legally. Type rating is for airman to legally operate the aircraft that required one. See type certificate of R22

@vasin1987 You are correct. A type certificate is required for an aircraft type to be legally operated regardless of whether its pilots are required to have a type rating to operate it.

SFAR 73 is Robinson R-22/R-44 Special Training and Experience Requirements and lists the specific training requirements for that model. Here's one relevant piece:

(1) No person may act as pilot in command of a Robinson model R-22
  unless that person:
(i) Has had at least 200 flight hours in helicopters, at least 50
  flight hours of which were in the Robinson R-22; or
(ii) Has had at least 10 hours dual instruction in the Robinson R-22
  and has received an endorsement from a certified flight instructor
  authorized under paragraph (b)(5) of this section that the individual
  has been given the training required by this paragraph and is
  proficient to act as pilot in command of an R-22. Beginning 12
  calendar months after the date of the endorsement, the individual may
  not act as pilot in command unless the individual has completed a
  flight review in an R-22 within the preceding 12 calendar months and
  obtained an endorsement for that flight review. The dual instruction
  must include at least the following abnormal and emergency procedures
  flight training: [...]

SFAR 108 has similar requirements for operating the Mitsubishi MU-2B.
Finally, note that the type certificate is for the aircraft, and has nothing to do with whether an individual pilot is qualified to fly it or not.

When I first read this, I missed the 'or' and the end of (1)(i) and I was really confused as to how you were supposed to get 50 hours in an R-22 if only 10 of it was dual instruction and you weren't allowed to act as PIC. - haha

It's important to note that SFAR73 is modeled after an aircraft type rating, and behaves as such.

Thanks, In summary 10 hours of dual to get a endorsement that last 12 months. And if you don't have 50 hours after 12 months you need to do a flight review before continuing to fly on it.

The FAA does indeed require model-specific type ratings for many aircraft (a list of aircraft which the FAA recognizes type ratings for is here). FAR 61.31 says that type ratings are required for

(1) Large aircraft (except lighter-than-air).
(2) Turbojet-powered airplanes.
(3) Other aircraft specified by the Administrator through aircraft
  type certificate procedures.

In this context, according to Advisory Circular 61-89E, "large" means it has a gross weight of 12,500 lbs or greater. In addition, based on (2) above, you need a type rating in the US to fly any jet, even small, single-engine jets or those designed specifically for single-pilot operation.

Purely for argument's sake, would a propfan-powered aircraft count as a "turbojet" for the purposes of FAR 61.31?  What about a turboprop?


text:
Do I need to use an airfield to take off or land a powered paraglider?
Most aircraft require a runway to take off and land, however powered paragliders simply attach to the pilot's back, requiring the pilot to run a few metres to take off. The landing distance is also very short.
Due to this, why would I use an airfield with a runway to take off and land at, considering only the first few metres are needed, and the pilot would be required to walk along an active runway for a long distance. Why not just use an empty field where there is no nearby traffic and you are not causing delays to flights?
Should I land/takeoff from a runway in spite of this, or simply use a suitable field within reasonable distance of the airfield? What are the regulations or best practices for this in the UK?

These things depend heavily on the jurisdiction and related regulations for anything from rules of the air to local environmental restrictions. Which jurisdiction do you have in mind?

I would expect a lot of airfields would object to having paragliders around, as they'd mix poorly with regular traffic.

This is in the UK. Powered paragliders don't normally have radios, but you could use a handheld one in theory for landing at a controlled airfield.

This is a question you should ask your instructor. Paramotors are known to kill people -- the recipe against getting killed contains learning from an instructor following a syllabus of exercises, among other things. During the instruction period you should try to experience several different kinds of situations, this might include how to interact with other flying objects.

In the UK a paramotor does not have to take off from an airfield. There is an explanation of the UK regulation of paramotors on the British Hang Gliding and Paragliding Association website.  You do need the landowner's permission to take off, but you don't need any type of pilot's licence.  You have to comply with the rules of the air (the ANO), as does any other flyer
Taking off from an airfield that is being used by faster aircraft (anything else with an engine is faster than a paramotor) may be a bad idea!

NOTE: My answer is US specific
Not only is there no need to operate from an airport, it is recommended not to, if there are aircraft operating from the airport. Paramotors operate (in the US) under FAR Part 103.

103.13 Operation near aircraft; right-of-way rules.
(a) Each person operating an ultralight vehicle shall maintain vigilance so as to see and avoid aircraft and shall yield the right-of-way to all aircraft.
(b) No person may operate an ultralight vehicle in a manner that creates a collision hazard with respect to any aircraft.
(c) Powered ultralights shall yield the right-of-way to unpowered ultralights.

In addition to the above,

103.15 Operations over congested areas.
No person may operate an ultralight vehicle over any congested area of a city, town, or settlement, or over any open air assembly of persons.

as well as

103.17 Operations in certain airspace.
No person may operate an ultralight vehicle within Class A, Class B, Class C, or Class D airspace or within the lateral boundaries of the surface area of Class E airspace designated for an airport unless that person has prior authorization from the ATC facility having jurisdiction over that airspace.

It is common to operate a paramotor from (launch from and land on) a park or other cleared field, as long as you don't launch over a large number of people. In my area of Virginia, there are some paramotor pilots who use a public park and launch themselves along an edge, so as not to fly over on-going soccer games.

you can not just go to a public field and take off. You need prior authorization from the owner (municipality). Remember that public is still a form of property. Should you just go on a municipal field and decide for yourself that is not crowded, then you’re trespassing and endangering. Looks like 5000$ fine. The proper way is to apply in writing. They will ask you how much area are you using. Based on that they will issue a license. You clearly mark the area in use for private event and install the windsock. However, if there are people around you should provide security. It’s complicated


text:
What is the reference chord for AoA measurement or calculation in a twisted wing?
Let us assume we have a rectangular, unswept wing with no dihedral and a given wing twist and we want to measure in flight or calculate its $c_L$ vs $\alpha$ (angle of attack) diagram. Of course each airfoil along the span will have a different local angle of attack at every flight attitude. Which y-coordinate along the span must (or should?) be used as a reference?

Angle of attack is always a local quality. The overall parameter is angle of incidence, and that is measured relative to the airplane's X coordinate.

As already answered, it is a matter of convention. For the whole aircraft, its longitudinal axis is usually used as a reference. The root chord, 25%-span chord, MAC and even the angle of zero lift can all be used. But if the aircraft has an AoA sensor, everything is usually calibrated in terms of this sensor indication (i.e. its local AoA), which may have very indirect relationship to the wing AoA.

In short: it’s up to the designer to pick any definition as long as the design and analysis always obeys that definition.
Usually, it’s a general practice to define a root chord and then calculate the rest of the local aoa‘s in relation to the root chord. This makes wing-strip calculations simpler. It’s also used in helicopter rotor blades and propellers.
On the other hand, there are numerous simplified calculations (that calculate wing or aircraft level properties) that may consider the mean aerodynamic chord. In this case, of course, the mac location would be used.

Thanks, that's what I suspected. I was curious to know  if it was a matter of convention.


text:
What are the communication procedures for flying from one Class D airspace directly into another Class D airspace?
What is the communication procedure for descending through Class D airspace to land at a different controlled airport in a separate class D airspace that is directly next to it, such as Long Beach (KLGB) and Los Alamitos (KSLI)?

I have not flown into this airspace. But, based on the location in question, you probably should be on flight following long before entering the Mode C Veil for the overlying Class B. If not, contact the Approach Control listed for the Class D into which you are flying. They will then coordinate your clearances through the respective airspaces until you are handed off to the final destination Class D controller for landing clearance.
Arrivals into KADS have a similar scenario. When getting your ATIS before arrival, you will be informed on the recording to contact approach on a specific frequency, give your destination as Addison, and that you have information A-Z. You are required to do this in order to land in KADS. You can not enter the Class B or the Class D without doing this first. Approach will handle your transition through any airspaces from there.


text:
What is the Saint-Venant formula for calculating equivalent air speed (EAS)?
I'm studying some ground exams (for a lapsed IR). In the course notes it says that EAS (Equivalent Airspeed, i.e. a compressibility-corrected airspeed) is calculated (e.g. by an aicraft's Air Data Computer) using the "Saint-Venant formula". The course notes don't actually give said formula.
I assume they are talking about this guy who derived a forerunner of the Navier-Stokes equations. However, most of his work seems to be to do with waves in shallow water and not aerodynamics. I think I know how EAS is calculated, and it doesn't seem to involve anything as hairy as Navier-Stokes (although it does require isentropic flow relations.) But I can't figure out how Saint Venant has anything to do with it. From another forum: "In the EASA learning objectives I can find no reference to 'Saint-Venant' so it is probably just something somebody thought up to confuse you." Can anyone shed any light on this?

I just read your question multiples times but I'm not sure I'm understanding it correctly. Is it "Which Saint-Venant the formula for calculating EAS is named after?" If so, you should edit your question, especially the title (there can be other most obvious question with such a title, it would help navigate among them without opening each one)

Good point. It looks like another user (Pondlife) edited it already. This makes it a more consistent question.

Have a look at http://zeteamfirst.free.fr/pilotage/anemo/asi_4.htm
It states the Saint Venant equation as being: \begin{equation}
Pt - Ps = \frac{1}{2}\rho V_p^2 \Bigl(1+\frac{M^2}{4}\Bigr)
\end{equation}
where:
$Pt$ : total pressure
$Ps$: static pressure
$\rho$: air density
$V_p$: TAS
$M$: Mach number calculated as ratio of TAS/speed of sound.
Edited: ROIMaison's reply with the reference to Flight Mechanics of High-Performance Aircraft, Nguyen, looks much better to me, and I am tempted to delete my answer, for 2 reasons:
1) except for the $(1+M^2/4)$ part, the equation above is exactly Bernoulli's equation for incompressible flow, and,
2) I am quite sure that a Machmeter can do its job without being able to measure air density directly. In Nguyen's text, air density is not needed in the equation, whereas it is needed in the above equation.
I might have been a little too happy about finding an answer to question its validity thoroughly. Lesson learned!

Both you and ROIMaison provided very helpful answers - first time I've seen an actual equation associated with the name. The two formulas are different but use different inputs. I might see if I can derive one from the other, to check. I upvoted both your answers and approved yours because it was first, but very grateful to both of you.

You're right that your formula is very similar to the bernouilli equation. I don't really understand how the Mach factor is derived. The equation I found is derived quite easily using the isentropic relations, that's why I was surprise that our two formulae look so dissimilar from each other. @Halzephron would be interested to see if it's possible to derive one from the other.

@Ugo, it's good that you didn't delete the answer. I've put both equations in Excel for increasing flight Mach numbers at sea level, and the numbers are very close (0.02% for M=0.1 to 0.56% for M=0.7), so it's an excellent approximation! I still don't get how the are connected (perhaps a Taylor expansion?)

I found this snippet
from Flight Mechanics of High-Performance Aircraft, by Nguyen here.
This answer follows directly from the isentropic equations.

Update
Ugo's answer is a Taylor series approximation of this answer.
Rewriting equation (3.41) from this answer to isolate $\Delta p$, and introducing the more customary $\gamma$ for $k$:
$$ \Delta p = p \left[ \Bigl( 1 + \frac{\gamma-1}{2} M^2\Bigr)^{\frac{\gamma}{\gamma-1}} -1 \right] $$
If we then take the Taylor series expansion around M=0 of everything in the square brackets, we end up with:
$$\Delta p  = p \left[ \frac{\gamma}{2}M^2 + \frac{\gamma}{8} M^4 + O(M^6) \right]$$
Ignoring  the higher order terms denoted by $O(M^6)$, this can be refactored as:
$$\Delta p =  p \left[\frac{\gamma}{2}M^2\left(1 + \frac{M^2}{4} \right)\right]$$
The multiplying factor can be rewritten using equation 5 from  NASA isentropic equations:
\begin{equation}
q = \frac{1}{2}\rho V^2 = \frac{\gamma}{2} p M^2
\end{equation}
to give:
$$\Delta p = \frac{1}{2}\rho V^2\left(1 + \frac{M^2}{4}  \right)$$
as desired.
As this is a 4th order Taylor series expansion around M=0, it's very accurate for lower speeds, however, accuracy decreases as the flight Mach number increases.

Thanks, this and Ugo's answer are the first time I've seen an actual equation associated with M. saint-venant. Your answers have prompted me to do some searching for his name in association with Mach meters instead of ASI's and this has yielded some more promising google hits than I was getting before.

You're welcome, it also took some effort for me to find a formula. I found this through books.google.com, and there were also some other books that popped up that might be interesting to you. You could have a look over there.